Actor and activist Matt Damon has announced plans to go on a "toilet strike" to raise awareness about the millions of global citizens without access to clean water.

The Bourne Identity star made the humorous declaration during a fake press conference, which was filmed and turned into a public service announcement (Psa) for his Water.org campaign.

During the hoax media chat, he told reporters, "In protest of this global tragedy, until this issue is resolved, until everybody has access to clean water and sanitation, I will not go to the bathroom."

Explaining the challenge, Damon said, "Anybody have any idea what invention has saved more lives than any other in the history of humankind? The toilet."

Turning serious, he added, "What's even more shocking is the catastrophic worldwide lack of clean water and sanitation. Seven hundred and eighty million people - that's twice the population of the United States - lack access to clean water. Two-point-five billion people lack access to a toilet or basic sanitation. I mean, more people have cellphones than have toilets."

The actor has even set up a special webpage for his campaign, StrikeWithMe.org, on which he encourages fans to support his strike and make their voices heard by spreading the news about the global water shortage to mark Water Day on 22 March (13).